The present invention relates to a fuel cell stack which generates electricity based on an electrochemical reaction between a fuel gas and an oxidizing gas, and to a seal structure between separators, in particular.
In general, a solid polymer type of a unit cell (unit battery) is composed of a membrane-electrode assembly (hereafter referred to as MEA; Membrane Electrode Assembly) consisting of an electrolyte membrane and a pair of electrodes arranged on both of the surfaces and a pair of separators sandwiching the MEA; and has a stacked shape as a whole. The unit cell generates an electric power between the electrodes when an oxidizing gas or a fuel gas is supplied to each of the electrodes through a gas channel formed in each separator.
A fuel cell with a stacked structure is composed by stacking a plurality of unit cells. As disclosed in Japanese Patent Laid-Open No. 2004-311056, for instance, a fuel cell stack is formed by arranging a terminal (electrode plate), an insulator and an end plate on both ends of a cell-stacked assembly in a cell-stacked direction, tightening the cell-stacked assembly in the cell-stacked direction, and fixing the cell-stacked assembly by using a fastener (tension plate, for instance) extending to the cell-stacked direction and a bolt on the outside of the cell-stacked assembly.